Nucleic acid sequencing is the process of determining the precise order of nucleotides within a nucleic acid, such as a DNA molecule or RNA molecule. For example, DNA sequencing has become essential in a variety of biological fields and research. The rapid speed of sequencing has become an important part of biotechnology in diagnostics, forensics, therapeutics, etc., for determining partial or complete nucleic acid sequences, or genomes.
A naturally-occurring double-stranded DNA (dsDNA) includes a linked chain of deoxyribose sugar as a backbone for four nucleotide bases (also referred to as nucleobases), e.g., including adenine (A), cytosine (C), guanine (G), thymine (T). These four nitrogen bases can form hydrogen bonds that hold two individual strands of the DNA together. For example, in naturally-occurring dsDNA, adenine bonds to thymine (A=T) and cytosine bonds to guanine (C≡G). The A=T and CG bonds are two different types of hydrogen bonds formed by the base pairs. Adenine forms two hydrogen bonds with thymine (A=T) and cytosine forms three hydrogen bonds with guanine (C≡G). For example, the energy of formation of N—H . . . O bonds is approximately 8 kJ/mol, and the energy of formation of N—H . . . N bonds is approximately 13 kJ/mol (e.g., where the dotted line represents the hydrogen bond). A naturally-occurring RNA molecule includes a linked chain of ribose sugar as a base for four nucleobases, e.g., including A, C, G, and uracil (U). For example, when RNA binds to DNA, an adenine nucleobase of DNA forms two hydrogen bonds with uracil nucleobase of RNA (A=U). RNA molecules are single stranded and can form many structural configurations.